1. Field of the Invention
The present invention generally relates to techniques for curing adhesives and more particularly relates to techniques for curing heat catalyzed adhesives.
2. Description of the Prior Art
There is a type of urethane adhesive widely used in the replacement auto glass industry which must be heated to at least 180.degree. F. prior to application in order to catalyze its curing process and improve its ability to be applied by means of a caulking gun. The only heater currently available for this purpose which may be installed in a vehicle for mobile auto glass replacement is operated from the service vehicle's 12 VDC electrical system.
Urethane adhesive is used to form a structural bond of the windshield and back lite to the vehicle. There are two major types of urethane adhesives which cure using different chemical reactions. Each type has its advantages and disadvantages. One type is a two part system in which the parts must be mixed prior to application. The second type uses temperature and humidity as its catalyst. A predominant supplier of the second type is Sika Industries. The Sika UltraFast.RTM. and SikaPlus Booster.RTM. urethane adhesives must be heated to 180.degree. Fahrenheit (F.) prior to application.
Auto glass replacement is a service industry in which mobile operation in the norm, I.e. the preponderance of all replacement is done at a location of the customer's choosing. This means that the installation must be accomplished out of a service vehicle. Sika manufactures a sealant heater for use in service vehicles. It is powered from the vehicle's 12 VDC electrical system, consumes about 150 Watts of power, and allows two tubes of sealant to be heated. Many windshields and back lites require more than one tube of adhesive and some require more than two. Further, the time between successive mobile installations is frequently under 30 minutes. The electrical sealant heaters do not provide sufficient heated sealant for some installations and the time required to heat additional tubes of sealant frequently exceeds the available interval between jobs.